Person: Sánchez Martínez, Sonia
Universidad Complutense de Madrid
Faculty / Institute
Mineralogía y Petrología
Petrología y Geoquímica
Now showing 1 - 10 of 52
PublicationGeochemistry and Sm–Nd isotopic sources of Late Ediacaran siliciclastic series in the Ossa–Morena Complex: Iberian–Bohemian correlations(Springer, 2021) Rojo-Pérez, Esther; Fuenlabrada Pérez, José Manuel; Linnemann, Ulf; Arenas Martín, Ricardo; Sánchez Martínez, Sonia; Díez Fernández, Rubén; Martín Parra, Luis Miguel; Matas, Jerónimo; Andonaegui Moreno, Pilar; Fernández Suárez, JavierThe Cadomian basement in central and southern Europe is composed by Ediacaran–Early Cambrian sequences that appear dismembered along the Variscan Orogen. These ancient series contain geochemical and isotopic keys related to their deposition in different basins located along the paleo margin of Gondwana. The southwest of Iberian Massif (Ossa–Morena Complex) contains an excellent representation of Cadomian basement. The oldest sedimentary succession of this region, the Serie Negra Group (c. 600–541 Ma), is composed by the Montemolín Formation which consists of metapelites, metagreywackes and abundant amphibolites; and the Tentudía Formation which consists of metagreywackes, black quartzites and metapelites. The whole-rock and Nd isotopic geochemistry of the Montemolín and Tentudía formations, are consistent with a deposition in a back-arc or fore-arc setting. Their Nd isotopic composition shows highly negative εNd(t) values in a range between − 6.9 and − 11.5, resulting in old Paleoproterozoic Nd model ages between 1.9 and 1.7 Ga. The Nd isotopic signatures obtained for the Cadomian basement in the Iberian Massif are almost identical to those obtained for equivalent sedimentary series in the Saxo-Thuringian Zone (Bohemian Massif), where Nd model ages range between 2 and 1.6 Ga. The limited variability of these Nd-TDM ages suggests that the southwestern Iberian and North Bohemian series shared a common source during Ediacaran times, which would be located close to the periphery of the West African Craton. The Nd isotopic data considered herein provide solid evidence about the peri-Gondwanan location and correlation between the Cadomian basement of southwestern Iberia and North Bohemia. PublicationThe Bazar Ophiolite of NW Iberia: a relic of the Iapetus–Tornquist Ocean in the Variscan suture(Blackwell Publishing Ltd, 2012) Sánchez Martínez, Sonia; Gerdex, Axel; Arenas Martín, Ricardo; Abati Gómez, JacoboThe Bazar Ophiolite, one of the ophiolitic units involved in the Variscan suture of NW Iberia, is mainly formed by metagabbroic high T amphibolites with N-MORB affinity. The ophiolite appears accreted under an arc-derived upper terrane affected by intermediate-P granulite facies metamorphism dated at 496– 484 Ma. U-Th-Pb geochronology and Lu-Yb-Hf isotope geochemistry of zircons allow recognizing two growth stages. The first occurred during crystallization of the gabbroic protolith and has been dated at 495 ± 2 Ma, whereas the second one, interpreted as dating the high T metamorphism, yielded an age of 475 ± 2 Ma. The chronology of the Bazar Ophiolite and its accretionary history suggest that this unit is a relic of the Cambrian ocean located to the North of Gondwana, the Iapetus–Tornquist Ocean, accreted to a dissected arc during or before the early stages in the opening of the Rheic Ocean. PublicationPaleogeografía geoquímica de las series metasedimentarias del Macizo Ibérico(Sociedad Geológica de España., 2016) Fuenlabrada Pérez, José Manuel; Arenas Martín, Ricardo; Sánchez Martínez, Sonia; Díez Fernández, Rubén; Pieren Pidal, Agustín PedroLas características geoquímicas e isotópicas de las series turbidíticas del Macizo Ibérico reflejan distintos escenarios tectónicos en la periferia de Gondwana. Estos cambios se observan en el registro sedimentario de la transición Ediacarense-Cámbrico, que tuvo lugar en el contexto general de un margen continental activo. TDM jóvenes y ɛNd menos negativos resultan característicos de cuencas sedimentarias más exteriores, con una importante contribución de material juvenil derivado del sector más activo del arco volcánico (metagrauvacas culminantes de las Unidades Superiores del Complejo de Órdenes). Las cuencas sedimentarias más próximas al continente se caracterizan por mayores aportes desde dominios alejados del arco activo que dan lugar a valores de TDM más antiguos y ɛNd muy negativos (metagrauvacas de las Unidades Basales del Complejo de Malpica-Tui). Una evolución desde contextos activos hasta otros más propios de márgenes pasivos se detecta con claridad en la transición Ediacarense-Cámbrico, y debe relacionarse con una disminución de la actividad del arco volcánico y la transición hacia un margen pasivo. El diagrama de fSm/Nd vs ɛNd confirma esta variación de los escenarios tectónicos asociados al margen de Gondwana, perfectamente registrados en los metasedimentos de diferentes sectores y unidades del Macizo Ibérico. PublicationEvolución tectónica del Macizo Ibérico durante la orogenia Varisca: colisión Gondwana - Laurrusia(Sociedad Geológica de España., 2016) Díez Fernández, Rubén; Arenas Martín, Ricardo; Pereira, M. Francisco; Sánchez Martínez, Sonia; Albert Roper, Richard; Martín Parra, Luis Miguel; Rubio Pascual, Francisco J.; Matas, J.La revisión de la evolución tectonometamórfica y magmática del Macizo Ibérico revela periodos de extensión y convergencia alternantes dentro de un proceso global de convergencia entre Gondwana y Laurrusia durante la formación de Pangea en el Paleozoico Superior. Fases dominadas por compresión a escala litosférica se caracterizan por el desarrollo de subducción oceánica y continental, generación de arcos magmáticos, cabalgamientos y procesos de acreción de litosfera continental y plegamiento. Eventualmente, la convergencia Varisca durante el Carbonífero produjo la transferencia de un conjunto de terrenos alóctonos peri-Gondwánicos, el denominado Alóctono Ibérico, sobre Gondwana. El Alóctono Ibérico muestra una impronta tectonometamórfica previa a ese proceso de transferencia fruto de la yuxtaposición temprana de Gondwana y Laurrusia tras el cierre del océano Reico en el Devónico Inferior. Las fases dominadas por fenómenos extensionales están representadas por la apertura de dos cuencas oceánicas efímeras a expensas de la corteza orogénica formada hasta el momento, primero en el Devónico Inferior-Medio, tras el cierre del Reico, y luego durante el Carbonífero Inferior, tras el emplazamiento del alóctono peri-Gondwánico. Seguidamente, un evento de extensión intra-orogénica durante el Carbonífero Inferior-Medio desmembró al Alóctono Ibérico en apilamientos individuales de unidades exóticas separados por fallas extensionales y domos. La tectónica transcurrente jugó un papel fundamental durante toda la orogenia Varisca, especialmente durante la creación de nuevos bloques tectónicos separados por zonas de cizalla transcurrentes intra-continentales en las últimas etapas de convergencia continental. PublicationFabric Development in a Middle Devonian Intraoceanic Subduction Regime: The Careón Ophiolite (Northwest Spain)(University of Chigaco Press, 2010) Gómez Barreiro, Juan; Martínez Catalán, José Ramón; Prior, D.; Wenk, H.-R.; Vogel, S.; Díaz García, Florentino; Arenas Martín, Ricardo; Sánchez Martínez, Sonia; Lonardelli, I.A Middle Devonian suprasubduction zone ophiolite, the Careo´n Unit (northwest Spain), displays amphibolite-facies ductile deformation fabrics related to the onset of the Rheic Ocean closure. Two different fabrics, an early high-T foliation and a subsequent lower-T foliation, each of which characterized by distinct deformation mechanisms, have been identified in two distinct crustal-scale shear zones of the same ophiolitic thrust sheet. Combined quantitative texture analysis by electron backscattered diffraction and time-of-flight neutron diffraction, were carried out on the shear zones and correlated with micro- and macrostructural data. The results indicate that the regional lineation and shear zone kinematics (east-west, top-to-the-east) represent fabrics developed essentially during the intraoceanic subduction of the Rheic Ocean, and their orientation may be considered a reference vector for convergence models in this part of the Variscan belt. PublicationThe Galicia–Ossa-Morena Zone: Proposal for a new zone of the IberianMassif. Variscan implications(Elsevier, 2016-06) Arenas Martín, Ricardo; Díez Fernández, Rubén; Rubio Pascual, Francisco J.; Sánchez Martínez, Sonia; Martín Parra, Luis Miguel; Matas, Jerónimo; González del Tánago y del Río, José; Jiménez Díaz, Alberto; Fuenlabrada, José M.; Andonaegui Moreno, Pilar; Garcia Casco, AntonioCorrelation of a group of allochthonous terranes (referred to as basal, ophiolitic and upper units) exposed in theNW and SW of the Iberian Massif, is used to propose a new geotectonic zone in the southern branch of theVariscan Orogen: the Galicia–Ossa-Morena Zone. Recent advances in SW Iberia identify most of the formerOssa-Morena Zone as another allochthonous complex of the Iberian Massif, the Ossa-Morena Complex, equiva-lent to the Cabo Ortegal, Órdenes, Malpica-Tui, Bragança and Morais complexes described in NW Iberia. Thenew geotectonic zone and its counterparts along the rest of the Variscan Orogen constitute an Internal VariscanZone with ophiolites and units affected by high-P metamorphism. The Galicia–Ossa-Morena Zone includes aVariscan suture and pieces of continental crust bearing the imprint of Ediacaran–Cambrian events related tothe activity of peri-Gondwanan magmatic arcs (Cadomian orogenesis). In the Iberian Massif, the general struc-ture of this geotectonic zone represents a duplication of the Gondwanan platform, the outboard sections beingjuxtaposed on top of domains located closer to the mainland before amalgamation. This interpretation offersan explanation that overcomes some issues regarding the differences between the stratigraphic and paleontolog-ical record of the central and southern sections of the Iberian Massif. Also, equivalent structural relationships be-tween other major geotectonic domains of the rest of the Variscan Orogen are consistent with our interpretationand allow suspecting similar configurations along strike of the orogen. A number of issues may be put forward inthis respect that potentially open new lines of thinking about the architecture of the Variscan Orogen. PublicationGeochemistry of the Ediacaran–Early Cambrian transition in Central Iberia: Tectonic setting and isotopic sources(Elsevier, 2016-06) Fuenlabrada Pérez, José Manuel; Pieren Pidal, Agustín Pedro; Díez Fernández, Rubén; Sánchez Martínez, Sonia; Arenas Martín, RicardoA complete Ediacaran–Early Cambrian stratigraphic transition can be observed in the southern part of the Central Iberian Zone (Iberian Massif). Two different stratigraphic units, underlying Ordovician series, display geochemical and Sm–Nd isotopic features in agreement with an evolving geodynamic setting. Pusa Shales (Early Cambrian) rest unconformably on greywackes of the Lower Alcudian Formation (Late Ediacaran). Both sequences present minor compositional variations for major and trace element contents and similar REE patterns, close to those of PAAS (Post Archean Australian Shale). Trace element contents and element ratios suggest mixed sources, with intermediate to felsic igneous contributions for both units. Tectonic setting discrimination diagrams for the Ediacaran greywackes indicate that these turbiditic series were deposited in a sedimentary basin associated with a mature active margin (volcanic arc). However, the compositions of the Cambrian shales fit better with a more stable context, a back-arc or retro-arc setting. εNd(T) and TDM ages are compatible with dominance of a similar cratonic source for both sequences, probably the West Africa Craton. εNd565 values for the Ediacaran greywackes (−3.0 to −1.4) along with TDM ages (1256–1334 Ma) imply a significant contribution of juvenile material, probably derived from the erosion of the volcanic arc. However, εNd530 values in the Cambrian shales (−5.2 to −4.0) together with older TDM ages (1444–1657 Ma), suggest a higher contribution of cratonic isotopic sources, probably derived from erosion of the adjacent mainland. Coeval with the progressive cessation of arc volcanism along the peri-Gondwanan realm during the Cambrian, there was a period of more tectonic stability and increasing arrival of sediments from cratonic areas. The geochemistry of the Ediacaran–Cambrian transition in Central Iberia documents a tectonic switch in the periphery of Gondwana, from an active margin to a more stable context related to the onset of a passive margin. PublicationU-Pb geochronology and isotopic geochemistry of adakites and related magmas in the Ediacaran arc section of the SW Iberian Massif: The role of subduction erosion cycles in peri-Gondwanan arcs(Elsevier, 2022-04-22) Rojo-Pérez, Esther; Linnemann, Ulf; Hofmann, Mandy; Fuenlabrada Pérez, José Manuel; Zieger, Johannes; Fernández Suárez, Javier; Andonaegui Moreno, Pilar; Sánchez Martínez, Sonia; Díez Fernández, Rubén; Arenas Martín, RicardoIn the peri-Gondwanan Ediacaran arc section outcropping in the SW of the Iberian Massif (Mérida region), changes in the subduction angle and subduction rate, variable participation of highly modified mantle sources together with the role of old crustal material and juvenile mafic rocks driven by the incoming slab, occur with a recognizable cyclicality and can be traced according to the geochronology, geochemistry and isotopic sources of the magmatic bodies. Our results support the initial existence of a mantle wedge highly modified due to percolation of significant volumes of variably old crustal materials, whose isotopic sources are almost identical to those found in the oldest known metasedimentary sequence described in SW Iberian Massif, the Serie Negra Group. Old crustal sources, analogous to those of this series were introduced to high depths by common subduction an also probably by significant subduction erosion. During the oldest period recorded in the study arc section, between c. 602 and c. 550 Ma, subduction episodes that involve high rates of crustal material along with an eventual incorporation of mafic and ultramafic materials from the incoming oceanic plate, favoured by low subduction angles, lead to the generation of more silicic magmas with adakitic geochemical affinity and isotopic signature (Nd-Sr) with crustal tendency. However, an increase in the subduction angle and change to a roll-back stage dated at c. 540 Ma, caused significant decrease in the access of cortical material to the subduction channel, favouring generation of typical calc-alkaline magmas derived from the modified mantle wedge, which is also consistent with more juvenile Nd-Sr ratios. The correlation found between the magmatic events and the involved tectonic processes suggests that subduction erosion mechanisms have been very likely underestimated as active dynamic processes along the peri-Gondwana margin during at least Neoproterozoic to Early Cambrian times. PublicationReconstruction of the prograde PT history of high‐P migmatitic paragneisses via melt‐reintegration approach and thermodynamic modelling (Allochthonous Complexes, NW Iberian Massif)(Wiley, 2020) Novo Fernández, Irene; Albert Roper, Richard; Arenas Martín, Ricardo; Garcia Casco, Antonio; Díez Fernández, Rubén; Sánchez Martínez, SoniaThe Upper Units of the allochthonous complexes of the NW Iberian Massif constitute a terrane with continental affinity. They represent the vestiges of a Cambrian magmatic arc developed in the periphery of Gondwana (West African Craton) which was involved in the Devonian Variscan collision, undergoing high‐P, high‐T metamorphism. This includes ultramafic rocks, high‐P mafic rocks (eclogites and granulites) and high‐P migmatitic paragneisses. The latter rocks show an extensive migmatization with the leucosomes oriented parallel to the regional foliation. The migmatitic paragneisses are composed of garnet, kyanite, biotite, quartz, plagioclase, K‐feldspar, rutile and Ti‐hematite. Thermodynamic modelling using the measured bulk composition in the NCKFMASTHO system indicates metamorphic peak conditions of ~15 kbar and ~800 to 835°C, followed by a significant cooling. The prograde evolution is assessed by means of a melt‐reintegration approach, using the composition of the garnet and its inclusions. An appropriate composition of liquid is added to the measured bulk composition to emulate the pre‐melting bulk composition. Modelling of this melt‐reintegrated composition allows to identify a colder high‐P episode below ~500°C. Zircon crystals extracted from the leucosomes show overgrowths crystallized from the partial melt at c. 389 Ma (U–Pb system). The P–T–t path proposed reveals a subduction of the peri‐Gondwanan arc‐derived section down to mantle depths. An isobaric heating stage occurred as a result of residence at great depths and/or inception of a transient oceanic basin at c. 395 Ma. The ensuing near‐isothermal exhumation occurred due to the extension related to the inception of the basin, reaching the thermal peak shortly before c. 389 Ma. Subsequent cooling is related to the underthrusting of colder oceanic and transitional crust below the HP‐HT Upper Units. PublicationSpace and time in the tectonic evolution of the northwestern Iberian Massif: Implications for the Variscan belt.(The Geological Society of America, 2007) Martínez Catalán, José Ramón; Arenas Martín, Ricardo; Díaz García, Florentino; González Cuadra, Pablo; Gómez Barreiro, Juan; Abati Gómez, Jacobo; Castiñeiras García, Pedro; Fernández Suárez, Javier; Sánchez Martínez, Sonia; Andonaegui Moreno, Pilar; González Clavijo, Emilio; Díez Montes, Alejandro; Rubio Pascual, Francisco J.; Valle Aguado, Beatriz; Hatcher, Robert D.; Carlson, Marvin P.; McBride, John H.; Martínez Catalán, José RamónRecent advances in geochemical studies of igneous rocks, isotopic age data for magmatism and metamorphism, quantitative pressure-temperature (P-T) estimates of metamorphic evolution, and structural geology in the northwestern Iberian Massif are integrated into a synthesis of the tectonic evolution that places the autochthonous and allochthonous terranes in the framework of Paleozoic plate tectonics. Because northwestern Iberia is free from strike-slip faults of continental scale, it is retrodeformable and preserves valuable information about the orthogonal component of convergence of Gondwana with Laurentia and/or Baltica, and the opening and closure of the Rheic Ocean. The evolution deduced for northwest Iberia is extended to the rest of the Variscan belt in an attempt to develop a three-dimensional interpretation that assigns great importance to the transcurrent components of convergence. Dominant Carboniferous dextral transpression following large Devonian and Early Carboniferous thrusting and recumbent folding is invoked to explain the complexity of the belt without requiring a large number of peri-Gondwanan terranes, and its ophiolites and highpressure allochthonous units are related to a single oceanic closure. Palinspastic reconstruction of the Variscan massifs and zones cannot be achieved without restoration of terrane transport along the colliding plate margins. A schematic reconstruction is proposed that involves postcollisional strike-slip displacement of ~3000 km between Laurussia and Gondwana during the Carboniferous.